Use of a spindle to provide optical fiber in a wellbore

ABSTRACT

A method of providing optical fiber in a wellbore may include lowering a spindle holding the optical fiber through the wellbore and anchoring a distal end of the optical fiber in the wellbore. The method may also include drawing the optical fiber from the spindle by pulling the spindle back through the wellbore. A device for providing optical fiber in a wellbore may include a spindle configured to hold at least a portion of the optical fiber as the spindle moves through the wellbore. The optical fiber is drawn from the spindle as the spindle passes through the wellbore.

TECHNICAL FIELD

This disclosure relates to a method of providing optical fiber in a wellbore. In particular to the use of a spindle to provide a portion of the optical fiber in a completed wellbore.

BACKGROUND

Sensors in subterranean wells can provide valuable information on the changes in the downhole environment either continuously or periodically, particularly in oil and gas wellbores. However, one of the challenges is the transmission of information between the sensors and the surface. Downhole fiber optics monitoring is universally accepted in the upstream industry as the technology of choice to elucidate flow processes in wellbore production or injection. Using optical fiber to monitor is now seriously considered for new completions due to advances in fiber development and cable manufacturing and the corresponding reduction in manufacturing cost and improvements in processing and visualization algorithms, etc.

Referring to FIG. 1, conventionally, a cable containing one or more optical fibers 5 for observation of parameters relating to production is attached to an exterior of a casing 10 with clamps and other mechanical devices to transmit information from the sensors to the surface 15. The casing 10 with the cable attached thereto is lowered into the wellbore and secured in place with cement 20. Some believe that the large cable, the clamps, or a combination cause the cement quality in the region of the optical fiber 5 to be compromised. In other words, the size of the cables used and the mechanical fixation methods limit the applicability of the installation.

Generally it has not been considered appropriate to attach elongated objects of a significant diameter to the casing 10 in the cement path because there is a risk that there will be insufficient penetration of cement in the interstices between the casing and object and between the object and the wellbore wall, which would therefore result in a leak path from formation to the surface. In turn, such a path is a risk to the integrity of the isolation from formation to surface and thus unacceptable on environmental and safety grounds.

Another challenge is that wellbore environments may have extreme conditions in terms of e.g. pressure, temperature, pH, or chemical environment. This has limited the possibility to attach sensors to the outer surface of a pipe without using clamps, as the attaching mechanism must first resist such extreme conditions and then have enough flexibility to follow the axial and circumferential geometry of the pipe.

Several clamp or clampless methods have been devised in the past that attempt to reduce the overall diameter/profile requirement, e.g., U.S. Pat. No. 8,942,529, U.S. Pat. No. 9,187,963, and U.S. Pat. No. 7,740,078. However, as with previous methods, the proposed solutions result in impracticality of replacement of damaged optical fiber 5. Furthermore, this and other known methods do not allow for effective gathering of distributed data from perforated or completed wells.

Other proposed solutions involve lowering the optical fiber 5 on a production tubing that goes past perforations. However, such methods can cause the production tubing to get stuck or can result in the perforations not having free communication with the wellbore, or both.

Other challenges pertaining to deployment of optical fibers may negate many of the possible advantages. For example, production downtime, requirements for talent and resources, reliability of the deployed fiber, possibilities of false positives due to faulty deployment, and the like can result in the benefits outweighing the costs.

The object of the invention is to overcome the limitations of the previous methods using a spindle to provide a portion of the optical fiber in the wellbore.

SUMMARY

A method of providing optical fiber in a wellbore may include lowering a spindle holding the optical fiber through the wellbore and anchoring a distal end of the optical fiber in the wellbore. The method may also include drawing the optical fiber from the spindle by pulling the spindle back through the wellbore.

Another method of providing optical fiber in a wellbore may include anchoring a proximal end of the optical fiber proximate an entrance to the wellbore and drawing the optical fiber from a spindle by lowering the spindle through the wellbore.

Another method of providing optical fiber in a wellbore may include lowering a spindle through the wellbore to a predetermined location within the wellbore, and drawing the optical fiber from the spindle toward an entrance to the wellbore.

A device for providing optical fiber in a wellbore may include a spindle configured to hold at least a portion of the optical fiber as the spindle moves through the wellbore. The optical fiber is drawn from the spindle as the spindle passes through the wellbore.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference to the accompanying drawings, wherein

FIG. 1 shows a prior art cross sectional view of an optical fiber cemented in a wellbore.

FIGS. 2-A through 2-C show a cross sectional view of steps as an optical fiber is placed in a wellbore in accordance with some embodiments described below.

FIGS. 3-A through 3-E show a cross sectional view of steps as an optical fiber is placed in a wellbore in accordance with other embodiments described below.

FIGS. 4-A through 4-F show a cross sectional view of steps as an optical fiber is placed in a wellbore in accordance with other embodiments described below.

FIGS. 5-A though 5-C show a cross sectional view of steps as an optical fiber is placed in a wellbore in accordance with other embodiments described below.

FIGS. 6-A through 6-D show a cross sectional view of steps as an optical fiber is placed in a wellbore in accordance with other embodiments described below.

FIGS. 7A through 7D show a cross section view of steps as an optical fiber is placed in a wellbore in accordance with yet other embodiments described below.

DETAILED DESCRIPTION

In one method, the optical fiber is provided in the wellbore 25 via a spindle 85. Referring to FIG. 2-A, the spindle 85 holding the optical fiber is lowered through the wellbore 25 on a wireline 115. As shown in FIG. 2-B, a distal end 50 of the optical fiber is then anchored in the wellbore 25. Then, as illustrated in FIG. 2-C, the spindle 85 is pulled back through the wellbore 25 thereby drawing the optical fiber from the spindle.

Anchoring the distal end 50 may involve magnetically or otherwise attaching the distal end 50 to a casing 10 or other element in the wellbore 25. Alternatively, as illustrated in the figures, anchoring the distal end 50 may involve providing an anchor 90 in the wellbore 25 and attaching the distal end 50 of the optical fiber 5 to the anchor 90.

In some instances, the wellbore 25 may be provided with a production tubing and the step of anchoring may involve providing the anchor 90 downhole of a distal end of the production tubing. Similarly, the step of lowering the spindle 85 in a wellbore 25 with production tubing may involve lowering the spindle 85 through the production tubing. In some instances, the production tubing may already be present in the well, in which case, the step of providing the production tubing would be passive. However, in other instances, the step of providing the wellbore (25) with the production tubing may include lowering the production tubing into the wellbore. While the production tubing would generally be in place prior to the method described in these figures, the method is not dependent on the presence of the tubing. In fact, it is conceivable that the production tubing could be placed after the optical fiber 5 is placed in the wellbore 25 in conjunction with any of the methods described in this document.

When an anchor 90 is used, the step of providing the anchor 90 may occur prior to the step of lowering the spindle 85. Alternatively, the anchor 90 and the spindle 85 may be lowered together on a slickline, e-line, coil tubing, or the wireline 115.

Another method of providing optical fiber 5 in the wellbore 25 may install the optical fiber in a similar but reversed manner. Referring now to FIG. 3-A, a proximal end 55 of the optical fiber 5 may be anchored proximate an entrance to the wellbore 25. Referring to FIG. 3-B, the spindle 85 may then be lowered through the wellbore 25 thereby drawing the optical fiber 5 from the spindle 85. As is shown, the spindle 85 may move through the wellbore in a manner to ensure that the optical fiber 5 is attached to the wellbore 25. While not shown in this particular example, this method would work equally well if the wellbore 25 were provided with production tubing. In such a scenario, lowering the spindle 85 would simply involve lowering the spindle 85 through the production tubing. An optional anchor may be provided downhole of a distal end of the production tubing and the distal end of the optical fiber 5 may be attached to the anchor.

In any of the methods, the step of providing the anchor 90 may involve lowering the anchor 90 before drawing the optical fiber 5 from the spindle 85. However, it is generally thought possible to lower the anchor 90 and the spindle 85 simultaneously.

Referring now to FIG. 3-C, the fiber 5 may be anchored in the wellbore 25 and the spindle 85 may be retrieved, e.g., via wireline 115 as illustrated in FIGS. 3-D and 3-E, leaving the optical fiber 5 in the wellbore 25. Alternatively, the spindle 85 may be dissolvable or may simply otherwise be left in the wellbore 25.

As illustrated, the optical fiber 5 may be affixed to an interior of the wellbore 25 in the above-described examples. Affixing the optical fiber 5 may include gluing, taping, or any other method of attaching the optical fiber 5 to an interior of the wellbore 25. Thus, the optical fiber 5 may be an integral part of a fabric that may stick by itself or be pasted to an interior diameter of the wellbore 25. Alternatively, affixing the optical fiber 5 to the wellbore 25 may involve the use of magnets, which are allowed to hold the optical fiber 5 in an interior of the wellbore. When there is a casing or production tubing or any other tubular in the wellbore, affixing the optical fiber 5 may simply mean affixing the optical fiber to an interior of the tubular.

Referring briefly to FIGS. 4-A to 4-F, the steps involved when a production tubing is present are very similar to those described with respect to FIGS. 3-A to 3-D, with the only notable difference being that before the actions of FIG. 3-A, a production tubing 30 is placed as shown in FIG. 4-A. The remaining steps would be similar to those described above and are thus not repeated.

Referring now to FIGS. 5-A through 5-C, the spindle 85 may be configured to act as the anchor. In such case, some steps as described with respect to FIGS. 3-A through 3-E may be omitted. For example, there may be no need for the anchor 90 or the associated steps involving the anchor 90. Thus, the step of lowering the spindle 85 may be simpler and involve lowering the spindle 85 through the wellbore 25 to a predetermined location within the wellbore 25. Then the spindle 85 may be set or otherwise engage the wellbore 25 at a location suitable to provide the optical fiber 5 in the desired location. Other steps described above may be utilized as appropriate. For example, the proximal end 55 of the optical fiber 5 may be anchored proximate the entrance to the wellbore as shown in FIG. 5-A. Then, the optical fiber 5 may be drawn from the spindle 85 by lowering the spindle 85 through the wellbore 25 as illustrated in FIG. 5-B. Then, when the spindle 85 has reached the predetermined location within the wellbore 25, as shown in FIG. 5-C, the spindle 85 may act as an anchor while readings are taken from the optical fiber 5.

Referring now to FIGS. 6-A through 6-D, a method of providing optical fiber 5 in the wellbore 25 may include lowering the spindle 85 through the wellbore 25 as shown in FIG. 6-A until the spindle 85 reaches a predetermined location within the wellbore 25 as shown in FIG. 6-B. Then, as illustrated in FIGS. 6-B and 6-C, the optical fiber 5 may be drawn from the spindle 85 toward the entrance to the wellbore 25.

Drawing the optical fiber 5 from the spindle 85 may utilize a float 125 as illustrated. In such cases, the proximal end 55 of the optical fiber 5 may be attached to the float 125 prior to the lowering of the spindle 85 through the wellbore 25. Then, once the spindle 85 has reached the predetermined location as illustrated in FIG. 6-B, the float 125 may be triggered or may otherwise be freed to disengage from the spindle 85 and thus be allowed to move upward to the entrance of the wellbore 25, as illustrated in FIG. 6-C. Once the proximal end 55 of the optical fiber 5 has reached the entrance of the wellbore 25, the proximal end 55 may be anchored proximate the entrance to the wellbore 25, as illustrated in FIG. 6-D.

Referring now to FIGS. 7A through 7D, a method of providing optical fiber 5 in the wellbore 25 may include arranging the spindle 85 at surface 15. The spindle 85, or a housing enclosing the spindle, may for instance be attached to the wellhead of the wellbore 25. In an embodiment, the distal end 55 of the fiber 5 may be provided with a weight 140, to draw the distal end 55 into the wellbore assisted by gravity.

FIG. 7A shows an attachment on the surface that houses the fiber spool 85 and drops the fiber 5 into the wellbore 25.

FIG. 7B shows the fiber 5 going down.

FIG. 7C shows when the fiber 5 is in the well 25 and we can take data.

FIG. 7D shows the fiber 5 being reeled back out from the wellbore 25.

In accordance with the various steps described, a device may be utilized to provide the optical fiber 5 in the wellbore 25. That device may include a spindle 85 and an optional mechanism for affixing the optical fiber 5 to an interior of the wellbore 25. The spindle 85 may be configured to hold at least a portion of the optical fiber 5 as the spindle 85 moves through the wellbore 25, such that the optical fiber 5 can be drawn from the spindle 85 as the spindle 85 passes through the wellbore 25. Thus, the spindle 85 may be capable of deploying the anchor 90 or alternatively the spindle 85 may itself act as an anchor and the anchor 90 may be omitted. In any event, the spindle 85 as described in the various embodiments above is configured to be placed within the wellbore 25 and hold at least a portion of the optical fiber 5 as the optical fiber 5 is drawn from the spindle 85.

Notably, while the perforations 75 are shown in a cemented section of the wellbore 25, it is possible to use the methods described to place the anchor 90, a portion of the optical fiber 5, or other elements in areas that are below the casing 10. Likewise, while a primary completion is shown, the method may be used in a retrofit operation. In such instance, prior to the steps indicated above, the existing production tubing (not shown) might be pulled from the wellbore 25.

In this manner, the optical fiber 5 can be introduced after the casing 10 is already secured in place with cement 20. Thus, one or more optical fibers 5 may be deployed for downhole monitoring by means of recompletion of an existing well. It is believed that the methods described may be useful in both vertical and deviated wells by carrying the optical fiber 5 past perforations 75 without inhibiting the flow therethrough. This may also allow good thru-tubing access to the payzone.

Conventionally, robust cables have been used to provide protection of optical fibers used in harsh environments such as wellbores. However, if optical fibers can be placed at a point in time when fewer impacts from wellbore tools and other likely damaging conditions are expected, the redundancy and protective bulk may be reduced or even eliminated, allowing for more working space in the wellbore. In some instances, the optical fibers may still become damaged after one or more operations. However, the expected cost of running a replacement optical fiber is believed to be very low as compared to the cost of running the conventional optical fibers encased in cable at the conventional time (i.e., at completion). Thus, while the foregoing description might be applicable to conventional cable-encased optical fibers, additional advantage may be attained using unconventional optical fiber configurations. For example, the optical fiber may be constructed with Kevlar reinforcing, glass coating, glass encapsulation, Teflon, resin soaking, braiding, spinning, spooling, weaving, yarns, multiple reels, etc. The relatively slim profile of these unconventional optical fiber configurations, as compared to conventional cables, may allow for fiber placement at a much later point in the process, allowing placement to be tailored for the specific application. In some instances, if the fiber is slim enough, packers and other wellbore devices may be used with decreased risk of leakage as compared to a cable-encased fiber.

In the description above, the term “optical fiber” is intended to refer to a single thread or to a group of threads acting as a cohesive unit. Generally, optical fibers are constructed of glass. Also, glass fibers may be an integral part of a fiber thread. However, other materials may also be used as optical fibers, as will be appreciated by one having ordinary skill in the art.

The term “spindle” is intended to refer to, for instance, a device comprising a rotatable section, such as a rotatable cylinder, whereon the fiber can be wound. The spindle may refer to, or comprise, a spool, or spool-type device. The fiber can be unwound from the rotatable section of the device. The rotatable section may typically have an outer diameter matching the flexibility of the fiber, so that the fiber can be unwound from the rotatable section without damaging the fiber.

The present disclosure is not limited to the embodiments disclosed above, wherein various modifications are conceivable within the scope of the appended claims; features of respective embodiments may for instance be combined. 

1. A method of providing optical fiber in a wellbore, comprising: lowering a spindle holding the optical fiber through the wellbore; anchoring a distal end of the optical fiber in the wellbore; and drawing the optical fiber from the spindle by pulling the spindle back through the wellbore.
 2. The method of claim 0, wherein anchoring the distal end comprises: providing an anchor in the wellbore; and attaching the distal end of the optical fiber to the anchor.
 3. The method of claim 0, further comprising: providing the wellbore with a production tubing; wherein the step of anchoring comprises providing an anchor downhole of a distal end of the production tubing; and wherein the step of lowering the spindle comprises lowering the spindle through the production tubing.
 4. The method of claim 0, wherein the step of providing the wellbore with the production tubing comprises lowering the production tubing into the wellbore.
 5. The method of claim 0, wherein the step of providing the anchor occurs prior to the step of lowering the spindle.
 6. A method of providing optical fiber in a wellbore, comprising: anchoring a proximal end of the optical fiber proximate an entrance to the wellbore; drawing the optical fiber from a spindle by lowering the spindle through the wellbore.
 7. The method of claim 0, further comprising providing the wellbore with a production tubing, wherein lowering the spindle through the wellbore comprises lowering the spindle through the production tubing.
 8. The method of claim 0, further comprising: providing an anchor downhole of a distal end of the production tubing; and attaching a distal end of the optical fiber to the anchor.
 9. The method of claim 0, wherein providing the anchor comprises: lowering the anchor before drawing the optical fiber from the spindle.
 10. The method of claim 0, wherein the spindle is configured to act as an anchor, and wherein lowering the spindle comprises: lowering the spindle through the wellbore to a predetermined location within the wellbore.
 11. A method of providing optical fiber in a wellbore, comprising: lowering a spindle through the wellbore to a predetermined location within the wellbore; and drawing the optical fiber from the spindle toward an entrance to the wellbore.
 12. The method of claim 0, wherein the step of drawing the optical fiber from the spindle utilizes a float, the method further comprising: attaching a proximal end of the optical fiber to the float; and allowing the float to move upward toward the entrance to the wellbore.
 13. The method of claim 0, further comprising anchoring the proximal end of the optical fiber proximate the entrance to the wellbore.
 14. The method of claim 0, further comprising: affixing the optical fiber to an interior of wellbore. 15.-21. (canceled)
 22. A method of providing optical fiber in a wellbore, comprising: anchoring a spindle holding the optical fiber at surface; and drawing the optical fiber from the spindle by dropping the fiber into the wellbore.
 23. The method of claim 22 comprising: providing the distal end of the optical fiber with a weight, to draw the distal end of the fiber into the wellbore assisted by gravity.
 24. The method of claim 22, comprising the step of: drawing the optical fiber into the wellbore until the distal end of the fiber has reached a predetermined location in the wellbore.
 25. The method of claim 22, comprising the step of: taking data using the optical fiber arranged in the wellbore; and using the spindle to pull the optical fiber back out of the wellbore.
 26. The method of claim 0, further comprising: affixing the optical fiber to an interior of wellbore.
 27. The method of claim 0, further comprising: affixing the optical fiber to an interior of wellbore. 